The IXP422 CPU has 16 General Purpose Input/Output (GPIO) pins which are used to interface to external hardware. In the case of the FSG3, the GPIO pins are used to monitor the buttons, control the LEDs, connect to the RTC, IDE controller and USB 2.0 controller.
Note that the LEDs are controlled by some external controller - they are not directly connected to GPIOs.
| GPIO | IXP Ball | Function | Connected to: | Configured as: |
| GPIO[0] | Y22 | | | Input |
| GPIO[1] | W21 | | | Input |
| GPIO[2] | AC26 | | | Input |
| GPIO[3] | AA24 | | | Input |
| GPIO[4] | AB26 | Sync Button (0 = Pushed) | | Input |
| GPIO[5] | Y25 | PCI INTC (IRQ 22) | | Input |
| GPIO[6] | V21 | PCI INTA (IRQ 23) | | Input |
| GPIO[7] | AA26 | PCI INTB (IRQ 24) | | Input |
| GPIO[8] | W23 |
| GPIO[9] | V22 | Reset Button (0 = Pushed) | | Input |
| GPIO[10] | Y26 | Unplug Button (0 = Pushed) | | Input |
| GPIO[11] | W25 |
| GPIO[12] | W26 | I²C SDA | RTC - SDA | Input/Tristate |
| GPIO[13] | V24 | I²C SCL | RTC - SCL | Output |
| GPIO[14] | U22 | | | Input |
| GPIO[15] | U25 | | | Output |